Roll Observatory packages and add a roll script

packages/web_components/lib/interop_support.js

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Updates document.registerElement so Dart can see when Javascript custom
 // elements are created, and wrap them to provide a Dart friendly API.
 (function (doc) {
   if (window._dart_register_element_interop_support) return;
   window._dart_register_element_interop_support = true;
 
@@ skipping 106 matching lines @@
         }
         return originalGetUnknownTag(o, tag);
       };
     });
   }
 
   doc._registerDartTypeUpgrader = registerDartTypeUpgrader;
   doc._onlyUpgradeNewElements = onlyUpgradeNewElements;
   doc.registerElement = registerElement;
 })(document);